Extended optical range reflective system for monitoring motion of a member

ABSTRACT

A garment and system includes a monitoring fabric that exhibits a light reflection property and substantially no light transmission property when the fabric is illuminated with light having wavelength(s) in the range of 400 to 2200 nanometers. The amount of useful light reflected by the fabric into an aperture of acceptance defined with respect to an axis extending from the fabric relative to the amount of light lost to the aperture of acceptance detectably changes when the fabric stretches in response to motion, as the motion induced by physiological activity (e.g., heart rate). The system includes at least one radiation source and at least one radiation detector, with the detector disposed in the aperture of acceptance. The source and detector may be attached to the fabric in relative positions such that the reception of incident radiation by the detector is directly affected by a change in the amount of useful light reflected by the fabric into the aperture of acceptance as the fabric stretches in response to motion.

CROSS-REFERENCE TO RELATED APPLICATIONS

Subject matter disclosed herein is related to the following co-pendingapplications:

System for Monitoring Motion of a Member, U.S. application Ser. No.60/502,760; filed Sep. 12, 2003 in the name of Chia Kuo and George W.Coulston.

Blood Pressure Monitoring System and Method, U.S. application Ser. No.60/502,751; filed Sep. 12, 2003 in the names of George W. Coulston andThomas A. Micka.

Reflective System for Monitoring Motion of a Member, U.S. applicationSer. No. 60/502,750; filed Sep. 12, 2003 in the name of George W.Coulston;

Blood Pressure Monitoring System and Method Having Extended OpticalRange, U.S. application Ser. No. 60/526,187; filed Dec. 2, 2003 in thenames of George W. Coulston and Thomas A. Micka.

Extended Optical Range Reflective System for Monitoring Motion of aMember, U.S. application Ser. No. 60/526,429; filed Dec. 2, 2003 in thename of George W. Coulston.

Extended Optical Range System for Monitoring Motion of a Member, U.S.application Ser. No. 60/526,188; filed Dec. 2, 2003 in the name of ChiaKuo and George W. Coulston.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a fabric useful in a system for monitoringmotion, and to the monitoring system incorporating such fabric. One suchtype of motion that can be monitored is that associated with geometricchange in a body in response to physiological activity.

2. Description of the Prior Art

Heart rate monitors are known for measuring and reporting the heart beatof humans and animals. Such monitors receive signals from the pulsatingflow of blood synchronized with the periodic pumping activity of theheart. Typically, these well-known monitors detect the pulsating flow ofblood through a sensor in a chest belt or through a sensor clippedmechanically to an ear or finger. U.S. Pat. No. 5,820,567 (Mackie)describes a representative arrangement of a chest belt or an ear clipfor a heart rate sensing apparatus.

A chest belt is difficult to fit and often requires gel to wet thesensor electrodes prior to use. Tight chest belts for heart monitoringcan be uncomfortable if worn for a prolonged period. Mechanical sensorsthat clip to a finger or an ear can also be uncomfortable.

The QuickTouch™ heart monitor sold by Salutron Inc. (Fremont, Calif.94538, USA) eliminates the chest strap, finger or ear clip to measureheart rate in all phases of exercise. However, while eliminatingcumbersome wires and straps, two points of body contact are required inoperation. This device thus requires application of two fingers on awatch band, two hands on a treadmill, or two hands on a bicycle handlebar to give heart rate readings. As a result this device does nottotally free the subject from the monitoring process.

Systems that relieve the monitored subject from the discomfort of chestbelts or clip devices to the finger or ear, and from the inconvenienceof being restricted to the monitoring apparatus, have been disclosed.

U.S. Pat. No. 6,360,615 (Smela) discloses a monitoring system using agarment that detects motion in the body of the wearer through a straingauge implemented using a polypyrrole-treated fabric.

U.S. Pat. No. 6,341,504 (Istook) discloses a garment for physiologicalmonitoring comprising one or more elongated bands of elastic materialwith conductive wire formed in a curved pattern. When the garment isworn by a human, the elongation and relaxation of the fabric caused bygeometrical changes of the human frame induce electrical propertychanges in the conductive wire(s) of the garment. Such a system adds anadditional component of complexity to the fabric structure, which is notwell-suited to traditional garment design and construction.

U.S. Pat. No. 4,909,260 (Salem) describes a bulky waist belt system forphysiological monitoring.

U.S. Pat. No. 5,577,510 (Chittum) describes bulky chest and waist beltsfor physiological monitoring.

Patent Publication WO 9714357, Healthcare Technology Limited, GreatBritain discloses a monitor capable of generating an audio heartbeatmessage.

SUMMARY OF THE INVENTION

The present invention is directed to a fabric, garment, system, andmethod for monitoring motion of a member, and is believed particularlyuseful for the monitoring of the motion generated by geometric changesin the body of a subject in response to physiological activity. Bymonitoring such motion, a noninvasive measurement of a parametercharacterizing the physiological activity may be derived.

The fabric exhibits a light reflection property and substantially nolight transmission property when the fabric is illuminated with lighthaving a wavelength in the range of from about 400 nanometers to about2200 nanometers, and particularly in the ranges from about 400 to about800 nanometers and from about 700 to about 2200 nanometers.

The amount of useful light reflected by the fabric into an aperture ofacceptance, defined with respect to an axis extending from the fabricrelative to the amount of light lost to the aperture of acceptance,changes when the fabric stretches and recovers in response to motion.Such motion could be induced, for example, by geometric changes in thebody caused by physiological activity.

In the preferred instance the fabric is comprised of a plurality ofreflective yarns each having a coating of an electrically conductivematerial thereon knitted or woven with a second plurality of stretchableyarns. Each stretchable yarn is formed as a combination of a coveredelastic yarn and a hard yarn.

The fabric may be used as a monitoring patch in a variety of settingsincluding a garment or textile mantle.

The garment or textile mantle having the patch of monitoring fabricdisposed thereon or therein may be incorporated into a system formonitoring motion, such as the motion generated by geometric changes inthe body of a subject due to physiological activity. The system furtherincludes a source providing radiation with wavelength(s) in the range offrom about 400 nanometers to about 2200 nanometers, and particularly inthe ranges from about 400 to about 800 nanometers and from about 700 toabout 2200 nanometers. The system still further includes at least adetector responsive to incident radiation in the same wavelength rangeand sub-ranges.

The detector is located in an aperture of acceptance defined about anaxis extending from the fabric. The source and detector preferably areattached to the fabric in relative positions such that the reception ofincident radiation by the detector is directly affected by a change inthe amount of useful light reflected by the fabric into the aperture ofacceptance as the fabric stretches. Such changes occur when the fabricstretches in response to motion due to geometric changes in the body ofa subject S wearing the garment or in the body component having themantle thereon. A signal processor converts a signal from the detectorrepresentative of radiation incident thereon into a signalrepresentative of at least one predetermined physiological parameter ofthe subject wearing the garment.

Alternatively, the system can comprise more than a single radiationsource and more than a single radiation detector for each source. Insuch an alternative embodiment, the signal processor is responsive tosignals from more than a single radiation source and more than a singleradiation detector and converts these signals into a signalrepresentative of one or more predetermined physiological parametersassociated with the subject wearing the garment.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more fully understood from the following detaileddescription, taken in connection with the accompanying drawings, whichform a part of this application, and in which:

FIG. 1 is a stylized pictorial representation of a system for monitoringat least one physiological parameter of a subject S that includes agarment having a fabric in accordance with the present inventionincluded therein, where the garment is sized to be worn over the torsoof the subject S;

FIG. 2 is a stylized representation illustrating the reflective responseof the fabric of the present invention;

FIGS. 3A and 3B are diagrammatic views illustrating the operation of themonitoring system of the present invention;

FIG. 3C is a graphical representation of the change in the lightbalance, that is, the amount of useful light reflected by the fabricinto an aperture of acceptance relative to the amount of light lost tothe aperture of acceptance as the fabric stretches and recovers;

FIG. 3D is a graphical representation of a signal, periodic in time,representing the change in the light balance during stretching andrecovery of the fabric.

DETAILED DESCRIPTION OF THE INVENTION

Throughout the following detailed description similar referencecharacters refer to similar elements in all figures of the drawings.

FIG. 1 is a stylized pictorial representation of a motion monitoringsystem 10 in accord with the present invention as applied to the task ofmonitoring motion due to geometric changes of the body of a subject S inresponse to physiological activity. A noninvasive measurement of one ormore parameter(s) characterizing the physiological activity of thesubject S, such as heart or breathing rate, may be derived by monitoringsuch motion(s).

As seen in FIG. 1, the system 10 includes a garment 12 having at least aportion, or patch 14, formed from a monitoring fabric 16. The monitoringfabric 16 has an exterior or outer surface 16E presented to a viewer andan interior surface 16I presented to the body of the subject S. Thepatch 14 of the monitoring fabric 16, although shown as rectangular inFIG. 1, may take any convenient shape. For example, the patch may becircular, oval in shape, or may be any regular or irregular shape. Ifdesired, a portion or even the entirety of the garment 12 may be madefrom the monitoring fabric 16.

The monitoring fabric 16 in accordance with the present inventionexhibits a light reflection property and substantially no lighttransmission property when the fabric is illuminated with light having awavelength in the extended range from about 400 to about 2200nanometers. This range is extended in the sense that it encompasses bothnear infrared light and visible broad spectrum white light havingwavelengths in the visible spectrum.

As used herein the term “broad spectrum white light” means light havinga wavelength in the range from about four hundred (400) nanometers toabout eight hundred (800) nanometers.

As used herein the term “near infrared light” means light having awavelength in the range from about seven hundred (700) nanometers toabout two thousand two hundred (2200) nanometers. The wavelength of 805nanometers or the wavelength of 880 nanometers may be used for systemsoperating in the near infrared spectrum. Light having wavelength of 805nanometers is preferred.

FIG. 2 shows by way of a stylized diagrammatic illustration thereflective response of the fabric 16 in accordance with the invention.The amount of useful light reflected by the fabric 16 through anaperture of acceptance 27 changes as the fabric stretches and recovers.The aperture of acceptance 27 is shown by way of illustration in FIG. 2as an area of any predetermined shape (e.g., circular in FIG. 2) spaceda predetermined distance from the surface of the fabric 16 and centeredupon a predetermined reference axis 24 extending from the surface of thefabric 16.

The term “light balance” may be used throughout this application torefer to the amount of useful light reflected by the fabric relative tothe amount of light lost. The term “useful light” refers to that amountof light originally incident upon an illuminated region 17 of the fabricthat is reflected from the fabric 16 through an aperture of acceptance27 defined with respect to a reference axis 24 extending from the fabric16. “Lost light” refers to light originally incident upon an illuminatedregion 17 that is not reflected into the aperture of acceptance 27.

Light could be “lost” to the aperture of acceptance 27 for variousreasons. For example, movement of the fabric 16 causes light reflectedfrom the fabric 16 to diverge with respect to the axis 24 and miss theaperture of acceptance 27. Otherwise, incident light could become “lost”when absorbed into the material of which the fabric 16 is formed.

The monitoring fabric 16 used in the patch 14 can be made from areflective yarns, stretchable yarns any combination of reflective andstretchable yarn or any like material. In one exemplary construction afirst plurality of reflective yarns is combined with a second pluralityof stretchable yarns.

The yarns can be combined in any conventional manner including woven ornon-woven construction. For woven constructions, yarns can be combinedin plain weave, satin weave, twill weave or any other well knownconstructions. For non-woven constructions such as knit constructions,yarns can be combined by circular knit, warp knit or any other suitableknit construction. In circular knits, typical constructions are singlejersey (i.e. different structure in front and back) and double jersey(i.e. same structure in front and back). Warp knits may include tricotand raschel constructions where the tightness can be adjusted byadjusting the number of needles/inch or the stitch size.

Any suitable apparel denier and any suitable needle combination orwarp/weft intensity may be used in making the monitoring fabric. Eachreflective yarn may comprise a coating of a specularly reflectivematerial thereon. The coating may also be electrically conductive.Furthermore, the reflective yarn may be elastic. Each stretchable yarnis formed as a combination of an elastic yarn component and a hard yarncomponent.

In the preferred instance the reflective yarn is that yarn sold by LairdSauquoit Technologies, Inc. (300 Palm Street, Scranton, Pa., 18505)under the trademark X-static® yarn. X-static® yarn is based upon a 70denier (77 dtex), 34 filament textured nylon available from INVISTANorth America S. à r. I., Wilmington, Del. 19805, as product ID70-XS-34X2 TEX 5Z that is electroplated with electrically-conductivesilver.

Alternatively, another method of forming the monitoring fabric 16 is toscreen-print a pattern using an electrically conductive ink afterconstructing the yarns in any conventional woven or non-woven manner.Suitable electrically conductive inks include, but are not limited to,those sold by DuPont Microcircuit Materials, Research Triangle Park,N.C. 27709, as silver ink 5021 or silver ink 5096, and the like.

A screen-printed pattern of conductive inks must also allow the fabricto move. Preferably, the conductive ink does not affect the ability ofthe fabric to stretch and recover. One way to prevent affecting thestretch and recovery properties of fabric is to screen-print a patternof conductive ink(s) in the form of a matrix of dots. Such a dot matrixpattern provides full freedom for the yarns in the fabric to move, whilestill exhibiting desired light reflection and non-transmissionproperties.

The patch 14 of monitoring fabric 16 can alternatively be formed fromelastic and electrically conductive composite yarn comprising a coreyarn made of, for instance, LYCRA® spandex yarn wrapped with insulatedsilver-copper metal wire obtained from ELEKTRO-FEINDRAHT AG,Escholzmatt, Switzerland, using a standard spandex covering process. Thecore yarn may further be covered with any nylon hard yarn or polyesterhard yarn.

Stretchable yarn can be formed in any conventional manner. For example,the stretchable yarn can be formed as a combination of a covered elasticyarn and a hard yarn.

In one preferred embodiment, the covered elastic yarn can be comprisedof a twenty (20) denier (22 dtex) LYCRA® spandex yarn single-coveredwith a ten (10) denier (11 dtex) seven filament nylon yarn. LYCRA®spandex yarn is available from INVISTA North America S. à r. I.,Wilmington, Del. 19805. Alternatively, the elastic yarn component of thepresent invention may comprise elastane yarn or polyester bicomponentyarns such as those known as ELASTERELL-P™ from INVISTA S. à r. I. NorthAmerica Inc. of Wilmington, Del. The terms spandex and elastane are usedinterchangeably in the art. An example of a branded spandex yarnsuitable for use with the present invention is LYCRA®.

Synthetic bicomponent multifilament textile yarns may also be used toform the elastic yarn component. One preferred synthetic bicomponentfilament component polymer can be thermoplastic. The syntheticbicomponent filaments can be melt spun or formed in any other mannercommon in the art of filament formation. In the most preferredembodiment the component polymers can be polyamides or polyesters.

A preferred class of polyamide bicomponent multifilament textile yarnscomprises those nylon bicomponent yarns which are self-crimping, alsocalled “self-texturing”. These bicomponent yarns comprise a component ofnylon 66 polymer or copolyamide having a first relative viscosity and acomponent of nylon 66 polymer or copolyamide having a second relativeviscosity, wherein both components of polymer or copolyamide are in aside-by-side relationship as viewed in the cross section of theindividual filament. Self-crimping nylon yarn such as that yarn sold byINVISTA North America S. à r. I., Wilmington, Del. 19805 under thetrademark TACTEL® T-800™ is an especially useful bicomponent elasticyarn.

Some examples of polyester component polymers include polyethyleneterephthalate (PET), polytrimethylene terephthalate (PTT) andpolytetrabutylene terephthalate. In one preferred embodiment polyesterbicomponent filaments comprise a component of PET polymer and acomponent of PTT polymer in a side-by-side relationship as viewed in thecross section of the individual filament. One exemplary yarn having thisstructure is sold by INVISTA North America S. à r. I., Wilmington, Del.19805 under the trademark T-40™ Next Generation Fiber.

The hard component could be made from any inelastic synthetic polymerfiber(s) or from natural textile fibers, such as wool, cotton, ramie,linen, rayon, silk, and the like. The synthetic polymer fibers may becontinuous filament or staple yarns selected from multifilament flatyarns, partially oriented yarns, textured yarns, bicomponent yarnsselected from nylon, polyester or filament yarn blends. The hardcomponent is preferably 260 denier (286 dtex) 68 filament nylon yarn.

Nylon yarns may comprise synthetic polyamide component polymers such asnylon 6, nylon 66, nylon 46, nylon 7, nylon 9, nylon 10, nylon 11, nylon610, nylon 612, nylon 12 and mixtures and copolyamides thereof arepreferred. In the case of copolyamides, especially preferred are thoseincluding nylon 66 with up to 40 mole percent of a polyadipamide whereinthe aliphatic diamine component is selected from the group of diaminesavailable from E. I. Du Pont de Nemours and Company, Inc. (Wilmington,Del. USA, 19880) under the respective trademarks DYTEK A® and DYTEK EP®.Further in accordance with the present invention, the hard yarn portionof the present invention may comprise polyesters such as, for example,polyethylene terephthalate, polytrimethylene terephthalate, polybutyleneterephthalate and copolyesters thereof.

The monitoring fabric 16 used in the patch 14 can be made according toany conventional textile means, including warp knitting, weft knitting,weaving, braiding, or through non-woven construction. The yarns can becombined to achieve fabrics exhibiting varying elasticity, including butnot limited to weft elastic, warp elastic or bielastic fabrics.

The monitoring fabric 16 may also be formed from composite yarns inwhich the reflective and stretchable components are combined in the sameyarn. Such a composite yarn would include a covering yarn having aspectrally reflective outer surface that is wrapped about an elasticyarn component in one or more layers.

The remainder of the structure of the garment 12 may exhibit anyconvenient textile construction (e.g., knitting, weaving) and may bemade from any suitable textile filament apparel denier yarn.

In one embodiment, the monitoring fabric 16 used in the patch 14 isattached to the garment 12. The patch 14 could be sewn, glued, taped,buttoned, interwoven or attached to the garment by any conventionalmeans.

It alternatively lies within the contemplation of the invention that thegarment 12 may be formed entirely from the monitoring fabric 16. Anysuitable needle combination or warp/weft intensity may be used for thegarment 12.

In another embodiment, the garment is seamlessly constructed of themonitoring fabric 16 using any suitable needle combination into thematerial of the remainder of the garment 12. In this context the term“seamless” refers to the known process of circular knitting on aseamless knitting machine (e.g., from Santoni S.p.A., Brescia, Italy).Garments processed in this way may possess minor seams, for example, theshoulder portion of a vest or the crotch seam of panty hose may beformed using traditionally practiced seaming methods. For these reasonsthe “seamless” term of art includes garments with one, or only a fewseams, and substantially constructed from a single piece of fabric.

One manner in which the fabric 16 can be made to exhibit the desiredreflective response with substantially no light transmission when thefabric is illuminated with light is to form the fabric in a denselywoven or tightly knitted fashion. Such a densely woven fabric may beobtained by weaving yarns of, for example, ten (10) to three hundred(300) denier (11 to 330 dtex) at a density of twenty (20) to sixty (60)warp and weft yarns per centimeter. A densely knitted fabric also may beobtained by increasing the needle count in the cylinder of a circularknitting machine, or gage of the fabric, while keeping the denier of theyarn constant.

Additionally, or alternatively, fabric density may be increased by apost-weaving or post-knitting shrinking or calendering step. Forexample, in order to obtain a densely woven or knitted reflective fabricof the invention, a widthwise and/or lengthwise shrinking of the fabricmay be obtained after wetting and re-drying on exposure to elevatedtemperature, about sixty (60) degrees Celsius and higher. Calenderingmay be performed by passing the woven or knit fabric through a nipformed between a pair of calender rolls to reduce fabric thickness anddensify the fabric.

Other well known means of increasing fabric density and tightening weavepatterns can be used to decrease or eliminate light transmission. Forexample, woven constructions can be tightened by increasing the warpends per cm and weft ends per cm in the construction. For non-wovenconstructions such as knit constructions, adjusting the number ofneedles/inch or the stitch size can decrease or eliminate lighttransmission through the fabric.

The system 10 shown in FIG. 1 is adapted for monitoring the motiongenerated by geometric changes of the body accompanying thephysiological activities of respiration or heart beat of the subject S.The garment 12 is thus configured similar to a vest or shirt, althoughother garment configurations are contemplated. For a vest-like orshirt-like textile structure, a contour and appropriate openings areformed for disposition on the torso of the subject S. For such use, thepatch 14 of monitoring fabric 16 should be located in a position ofmaximum sensitivity to geometric changes in the body of the subject S.For instance, the patch 14 could be used to monitor the beating heart orthe chest wall movement incident with respiration by disposing the patch14 beneath the nipple of the left breast of the subject S. It should beunderstood that the physical form of the garment may be appropriatelymodified for disposition over other parts of the body of the subject Sin the event it is desired to monitor the motion of another portion ofthe body which is associated with another physiological parameter.

The light balance is monitored as the monitoring fabric 16 stretches andrecovers. For this purpose, the system 10 further includes a suitablesource 18 of radiation operable in the wavelength range from about 400nanometers to about 2200 nanometers, and particularly in the wavelengthranges from about 400 to about 800 nanometers and from about 700 toabout 2200 nanometers. An associated detector 22 is located with respectto the fabric 16 along the reference axis 24 in the aperture ofacceptance 27. The detector 22 is responsive to incident radiation inthe given wavelength range and sub-ranges for producing signals inresponse thereto.

The source 18 is arranged in such a way as to maintain its relativeposition to the detector 22. For instance, the source and detector maybe rigidly connected together on one side of the fabric to maintain aspatial relationship. Alternatively, the source 18 and the detector 22can be maintained in any conventional manner determined by the user thatallows the detector to receive the radiation reflected from themonitoring fabric. Other well known means of maintaining the spatialrelationship of the source relative to the detector are contemplated.

In the case of operation with near infrared light, the radiation source18 can be a compound semiconductor-based (e.g., gallium arsenide orgallium aluminum arsenide) photo-emitting diode operating in theinfrared range (at a wavelength of 805 nanometers or 880 nanometers) orany similar radiation source. The radiation detector 22 can be anydevice that can detect radiation, for instance, a photodiode coupled toappropriately configured output amplification stages. Any well knownsemiconductors can be used for forming the photodiode, including siliconor germanium. A commercially available radiation source and detectorpackage suitable for use in the system of the present invention is thatavailable from Fourier Systems Ltd. (9635 Huntcliff Trace, Atlanta, Ga.,30350) as model DT155 (0-5 volt output).

For broad spectrum white light (400 to 800 nanometers) operation, thesource 18 can be a compound semiconductor-based “white LED” (e.g., alight emitting diode employing an indium gallium nitride based devicewith suitable phosphors to provide broad spectrum white light emission).The detector 22 is preferably a silicon phototransistor coupled toappropriately configured output amplification stages.

The radiation source 18 and the detector 22 are attached to monitoringfabric 16 in predetermined relative positions. The positions can bepredetermined such that the reception of incident radiation by thedetector 22 is directly affected by a change in the amount of lightreflected by the monitoring fabric 16 into the aperture of acceptance 27when the fabric stretches and recovers. In the preferred case, theradiation source 18 and detector 22 are embedded, or fixed firmly, intothe textile structure of the monitoring fabric 16. The radiation source18 and detector 22 can be fixed using any well known attachment method,including but not limited to, clamping, gluing, sewing, taping, or hookand loop fasteners (Velcro). Optionally, it may be desirable in someoperational configurations of the invention (e.g., when the subject S ison a treadmill) to dispose both the source and the detector remote fromand not in direct contact with the fabric 16. In such a remotearrangement, the radiation source 18 and detector 22 could be located inany arrangement that permits the detector 22 to detect changes in thereflection of radiation during stretch and recovery.

In the operational configuration shown in FIG. 1 (and discussed morefully in connection with FIGS. 3A and 3B) both the source 18 and thedetector 22 are mounted to the exterior surface 16E of the patch 14 ofmonitoring fabric 16. A suitable electrical source 26 for the radiationsource 18 may be conveniently carried in the garment 12. The electricalsource 26 can be any conventional electrical source known in the artincluding, but not limited to, a battery.

The system 10 may further comprise a signal acquisition and storage unit28 coupled to the detector 22 for storing signals produced thereby inresponse to incident radiation. Electrically conductive paths 32 areprovided in the garment 12 to interconnect the infrared source 18, thedetector 22, the electrical source 26 and the signal storage unit 28 inany appropriate electrical configuration.

One convenient manner of forming the conductive paths 32 is to knit orweave conductive filaments into the garment 12. A suitable conductivefilament for such use is the X-static® yarn mentioned earlier.Alternatively, the wires could be arranged so as to be unattached to thefabric.

Another method of forming the conductive paths 32 is to screen-print thepattern of conductive paths using an electrically conductive ink. Anyconductive ink could be used including, for instance, electricallyconductive inks sold by DuPont Microcircuit Materials, Research TrianglePark, N.C. 27709, as silver ink 5021 or silver ink 5096. Silver ink 5021ink is useful in fabricating low voltage circuitry on flexiblesubstrates, while silver ink 5096 is suggested for use in situationswhere extreme crease conditions are encountered. While silver ink 5021has a higher conductivity, silver ink 5096 is more easily spread andmore easily builds bridges among the fibers of the fabric of the garment12.

Once the signal is received by the radiation detector 22, a signalprocessor 34 may be used to convert the periodically varying signaloutput from the detector 22 representative of incident radiation thereoninto a signal representative of at least one (or a plurality) ofpredetermined parameter(s) (e.g., respiration rate, heart rate) of thesubject S wearing the garment 12. In the preferred instance the signalprocessor 34 comprises a suitably programmed digital computer. However,any signal processor known to those skilled in the art could be used.

The signals from the detector 22 stored within the storage unit 28 maybe transferred to the signal processor 34 in any convenient manner forconversion into signals representative of the physiological parameter(s)of the subject S. For example, transfer between the storage unit 28 andthe processor 34 may be effected by either a hardwired connection or athrough-space wireless (e.g., a wireless LAN using 2.4 GHz and 802.11a/bor 802.11g protocol known to skilled practitioners of the wireless highspeed data communications) or an optical transmission link, as suggestedin the area indicated by reference character 36 in FIG. 1.

The signal from detector 22 is a raw signal and comprises a composite offrequencies containing at least the respiration cycle and heart rate ofthe subject S. Certain noise sources contribute to the overall waveform.Such noise sources are believed to arise from extraneous motion of thesubject S or the monitoring fabric 16 and are not associated withrespiration and heart rate. These sources of noise could be filteredusing appropriate electronic filtering techniques. Specifically, highfrequency and low frequency pass filters appropriately chosen can createa cleaner raw overall waveform. Such filters could be selected accordingto methods known to those skilled in the art in order to obtain a signalassociated only with respiration or one associated only with heartbeat.Equivalently, filters to reduce known sources of signal noise are alsoeasily employed in the data acquisition system.

Although the signal processor 34 is illustrated in FIG. 1 is disposed ata location remote from the garment, it should be understood that it lieswithin the contemplation of the invention to implement the processor ina suitably sized package able to be physically mounted on the garment.In such an instance the output from the detector 22 may be directlybuffered into appropriate memory within the processor 34.

The operation of the motion monitoring system of the present inventionmay be more clearly understood with reference to FIGS. 3A through 3D. Asnoted earlier, both the source 18 and the detector 22 are mounted on oradjacent to the same surface of the monitoring fabric 16, typically theexterior surface 16E.

In the example illustrated in FIGS. 3A and 3B, the source 18 ispositioned to illuminate a generally circular spot indicated by thereference character 17. Using appropriate optics (e.g., an objectivelens on the source 18), the size of the spot 17 may be adjustablyselectable to focus on an area containing any arbitrary number of yarns16Y forming the fabric 16 or even to focus on an area containing only asingle filament of a yarn 16Y.

The source 18 is arranged in such a way as to maintain its relativeposition to the detector 22. For instance, the source 18 and detector 22may be rigidly connected together to maintain a spatial relationship.The radiation source 18 and detector 22 can be attached to themonitoring fabric 16 using a “clothes-pin” or alligator style clamp. Anywell known means of maintaining the spatial relationship of the source18 relative to the detector 22 could be used so that thephoto-responsive face of the radiation detector 22 lies in and iscoincident with the aperture of acceptance 27 defined with respect tothe reference axis 24 extending from the fabric 16.

The monitoring operation and system are discussed in the context ofmonitoring the periodic physiological activity of respiration. FIG. 3Aillustrates the fabric 16 in an unstretched state, while FIG. 3Billustrates the fabric 16 in a stretched state. The stretchingillustrated in FIG. 3B can be caused by movements such as the periodicphysiological activity of respiration. It should be noted that FIGS. 3Aand 3B are schematic and are not drawn to scale. For instance, thoughonly two dimensional movement of the fabric is shown, movement in alldirections is contemplated. As discussed above, any extraneous motionsof the subject S or monitoring fabric 16 could be filtered as noiseusing appropriate electronic filtering techniques.

As represented in FIG. 3A, in the unstretched state the filamentsforming the yarns 16Y of the monitoring fabric 16 lie within arelatively close distance of each other to define a pattern ofrelatively narrow gaps 16G. Four representative rays 18A, 18B, 18C and18D are illustrated to strike within the spot of illumination 17. Usingappropriate optics (e.g., an objective lens on the source 18), the sizeof the spot 17 may be adjustably selectable to focus on an areacontaining any arbitrary number of yarns 16Y forming the fabric 16 ordown to an area containing only a single filament of a yarn 16Y.

The rays 18A and 18B both define rays of “useful light” in that bothrays reflect from the surface 16E of the fabric 16 and pass through theaperture of acceptance 27 for collection by the detector 22. Ray 18Areflects specularly from the surface 16E of the fabric 16 by interactionwith one of the filaments of a yarn 16Y comprising the fabric 16. Ray18B is shown as being capable of entry into and escape from the volumeof a filament of a yarn 16Y. As FIG. 3B shows by the nonadjacent entryand exit points of ray 18B in the yarn, a ray could be directed throughmultiple internal reflections before emerging from a filament toward theaperture of acceptance 27. Although this mechanism may affect the amountof light received by detector 22, rays such as 18B are not believed tosignificantly affect the invention.

The rays 18C and 18D are rays of “lost” light. The ray 18C in FIG. 3Ainteracts with one of the filaments 16Y comprising the fabric 16 andreflects in a divergent path away from the axis 24. The ray 18C thusdoes not pass through the aperture of acceptance 27. As a result, theray 18C is not collected by the detector 22 and becomes “lost” light.The ray 18D interacts with one of the filaments 16Y of fabric 16 and isnot reflected from, but instead, is absorbed into the fabric 16. Such aray 18D does not enter the aperture of acceptance and is also light“lost” to the detector 22. Light is similarly “lost” when a ray (notshown) undergoes multiple reflections within the yarn and emerges from afilament, but is directed away from the aperture of acceptance 27.

As seen from FIG. 3B, as the fabric stretches, the size of the gaps 16Gformed in the monitoring fabric 16 increases. This increase in size ofthe gaps 16G decreases the likelihood that a photon will usefullyreflect toward the detector 22. Thus, the number of rays of useful light(e.g., the ray 18A) decreases from the situation shown in FIG. 3A, whilethe number of photons lost to the detector 22 by divergence or othermechanisms (e.g., represented by the rays 18B and 18C) increases. Thesignal output from the detector 22 concomitantly drops. Although thenumber of photons absorbed (e.g., represented by the ray 18D) does notnecessarily change, the amount of yarn 16Y within the spot size 17decreases, and it becomes less likely that a ray will strike yarn 16Yand be reflected or absorbed.

As the body of the subject S contracts during an exhalation, the fabric16 undergoes the elastic recovery phase of its stretch. The gaps 16Greturn to their original size (FIG. 3A). A relatively large portion ofthe light is again usefully reflected toward the detector 22, increasingthe output signal therefrom.

Viewed consecutively these events define a stretch cycle of elongationand recovery. The signal generated at the detector 22 of the monitoringsystem varies from an initial state to an intermediate state and back tothe initial state, as represented by FIG. 3C. This figure graphicallyillustrates that during the course of a stretch cycle the light balance(reference character “LB” in FIG. 3C) of the fabric changes. Comparisonbetween the initial and inhalation states (indicated by respectivereference characters “I” and “II” in FIG. 3C) and between the inhalationand exhalation states (indicated by respective reference characters “II”and back to “I” in FIG. 3C) clearly shows that the amount of lightreflected by the monitoring fabric 16 through the aperture of acceptance27 for collection by the detector changes in a periodic fashion overtime as the fabric stretches. Note that light lost to the detector 22 byabsorption is neglected. Thus, in FIG. 3C, at the initial state (“I”)the useful light represented by the bottom portion below the “LB” isgreater than the lost light represented by the upper portion above the“LB”. In contrast, at the inhalation state (“II”), the useful lightrepresented by the bottom portion below the “LB” is less than the lostlight represented by the upper portion above the “LB”.

This periodic variation in light balance is represented by FIG. 3D as atime-varying signal from “I” to “II” to “I” synchronized with theelongation and recovery stages of fabric stretch. This signal is atemporal measure of the underlying physiological processes, whichprovide the forces causing the elongation and recovery.

Consecutive fabric stretch cycles of elongation followed by recoveryprovide a periodic variation in light balance synchronized in time(represented in FIG. 3D). Thus, fabric stretch cycles have an associatedfrequency driven by the frequency of an underlying physiologicalprocess. In order to measure the frequency or frequencies of anunderlying physiological process(es) or the frequency of any motiondriving a fabric stretch cycle, the output from the detector 22 isdirected to a data acquisition unit 28. Typically, the data acquisitionunit 28 includes a detector signal sampling rate, which isuser-selectable in software. For example, if the frequency of normalhuman respiration rate (15 to 20 per minute) is being measured, anappropriate detector signal sampling rate is selected of less than orequal to 100 Hertz. The sampled signal is optionally filtered withappropriately chosen high and low pass filters to create a cleaner rawsignal, performed in software or hardware. The resulting waveformacquired from the data acquisition unit 28 is downloaded to and storedin a suitable computer (e.g., Dell Computer Inc., Mobile Pentium III,750 MHz CPU). The stored time domain signal is resolvable into afrequency domain spectrum by software methods known to those skilled inthe art of using the Fourier frequency deconvolution algorithm. Anyfrequency greater than that of the chosen lowest frequency expected bythe Fourier method appears in the frequency domain spectrum and is thusidentifiable, e.g. the rate of respiration sought. Frequencies higher orlower than, for example, typical respiration rates are also resolvableby known variations in the signal processing technique using the Fouriermethod.

Those skilled in the art will also recognize that the principlesunderlying the invention as heretofore described can be applied in avariety of other situations where it is desired to monitor the motion ofa member. For example, in another embodiment the motion monitoringsystem of the present invention may be used to monitor movement of acomponent of a multicomponent structure.

The motion monitoring system for such a usage comprises a textilemantle, at least a portion of which is formed from the monitoringfabric. The term “textile mantle” encompasses any fabric structurecovering (in whole or in part) a component of a structure.

The textile mantle is disposed in any convenient manner over thecomponent whose motion is to be monitored. In the same way as heretoforediscussed a source 18 and a detector 22 are attached to the textilemantle in relative positions such that the amount of useful lightreflected from the fabric 16 through an aperture of acceptance 27 forcollection by the detector 22 relative to the amount of light lost tothe detector 33 changes as the fabric undergoes a stretch cycle inresponse to motion of the component.

It may be appreciated from the foregoing that the fabric, garment andsystem of the present invention provides a particularly usefulnoninvasive technique for the monitoring of one or more physiologicalparameters of a subject S without necessitating a change of clothing orthe use of a chest or body strap or clamp.

When the fabric is in use, as when incorporated into a garment ormantle, the stretch cycle of elongation and recovery changes, ormodulates, the amount of reflected by the monitoring fabric toward theaperture of acceptance.

Those skilled in the art, having the benefit of the teachings of thepresent invention as hereinabove set forth, may effect modificationsthereto. Such modifications are to be construed as lying within thescope of the present invention, as defined by the appended claims.

1. A system for monitoring at least one predetermined physiologicalparameter of a wearer, comprising: a garment comprising a fabricexhibiting a light reflection property and substantially no lighttransmission property when the fabric is illuminated with light havingwavelength(s) in the range of from about 400 to about 2200 nanometers;an aperture of acceptance defined with respect to an axis extending fromthe fabric; at least one source of radiation having wavelength(s) in therange of from about 400 to about 2200 nanometers to direct radiationonto the fabric; at least one detector disposed in the aperture ofacceptance to detect radiation having wavelength(s) in the range of fromabout 400 to about 2200 nanometers incident on the detector; a signalprocessor for converting a periodically varying signal output from thedetector or from a data acquisition unit associated with the detectorinto a signal representative of a predetermined physiological parameterof the garment wearer; and a conductive pathway disposed on or in thegarment connecting the detector and the signal processor; wherein thesource and detector are associated with the fabric in fixed relativepositions with respect to the aperture of acceptance such that receptionof incident radiation detected by the detector is directly affected by achange in the amount of useful light reflected by the fabric into theaperture of acceptance as the fabric periodically stretches and recoversfrom stretch in response to at least one predetermined physiologicalparameter of the garment wearer.
 2. The monitoring system of claim 1wherein the fabric comprises: a first plurality of reflective yarnsknitted or woven with a second plurality of stretchable yarns, whereineach stretchable yarn is formed as a combination of a covered elasticyarn and a hard yarn.
 3. The monitoring system of claim 1 wherein thefabric is detachable from the garment.
 4. The monitoring system of claim1 wherein the fabric is integral with the garment.
 5. The monitoringsystem of claim 1 wherein the signal processor is mounted on or in thegarment.
 6. A system for monitoring motion of a structures comprising: atextile mantle mounted to at least a portion of the structure, at leasta portion of the mantle being formed from a fabric exhibiting a lightreflection property and substantially no light transmission propertywhen the fabric is illuminated with light having wavelength(s) in therange of from about 400 to about 2200 nanometers, an aperture ofacceptance defined with respect to an axis extending from the fabric; atleast one source of radiation having wavelength(s) in the range fromabout 400 to about 2200 nanometers; at least one detector disposed inthe aperture of acceptance and responsive to incident radiation havingwavelength(s) in the range from about 400 to about 2200 nanometers toproduce a signal representative thereof; a signal processor forconverting a periodically varying signal output from the detector orfrom a data acquisition unit associated with the detector into a signalrepresentative of motion of the portion of the structure; and aconductive pathway disposed on or in the textile mantle connecting thedetector and the signal processor; wherein the source and detector areassociated with the fabric in fixed relative positions such that thereception of incident radiation by the detector is directly affected bya change in the amount of useful light reflected by the fabric into theaperture of acceptance as the fabric periodically stretches and recoversfrom stretch in response to motion of the portion of the structure. 7.The monitoring system of claim 6, wherein the source and detector areattached to the fabric.
 8. The monitoring system of claim 6 wherein thefabric comprises: a first plurality of reflective yarns knitted or wovenwith a second plurality of stretchable yarns, wherein each stretchableyarn is formed as a combination of a covered elastic yarn and a hardyarn.
 9. The system of claim 1 wherein the fabric exhibits the lightreflection property when illuminated with light having wavelength(s) inthe range from about four hundred (400) nanometers to about eighthundred (800) nanometers; wherein the source provides radiation havingwavelength(s) in the range from about four hundred (400) nanometers toabout eight hundred (800) nanometers; and wherein the detector respondsto radiation having wavelength(s) in the range from about four hundred(400) nanometers to about eight hundred (800) nanometers.
 10. Themonitoring system of claim 6 wherein the fabric exhibits lightreflection property when illuminated with light having wavelength(s) inthe range from about four hundred (400) nanometers to about eighthundred (800) nanometers; wherein the source provides radiation havingwavelength(s) in the range from about four hundred (400) nanometers toabout eight hundred (800) nanometers; and wherein the detector respondsto radiation having wavelength(s) in the range from about four hundred(400) nanometers to about eight hundred (800) nanometers.